The invention relates to a writing method and system for receiving write data without a backhitch after a synchronization request.
A tape recording device (hereinafter, also referred to as a tape drive or a drive) configured to write data to a tape medium (also referred to as a tape) such as a magnetic tape medium accumulates data temporarily in a buffer. The data stored in the buffer is generally written from the buffer to a tape medium at any timing convenient to the drive. A host ensures that all the data sent to the drive are written to the tape medium. In order to reliably ensure this data recording, the host sends the drive a command (a WriteFM Non Immediate command which is also referred to as a “WriteFM0”) for a forced writing of the data. Such a forced writing from the buffer to the tape medium is referred to as a “synchronization.”
Meanwhile, unless the traveling of the tape medium is stopped after occurrence of a synchronization, a gap is generated on the tape medium between data written in a preceding synchronization and data written subsequently. This results in a waste of a recording area in the tape medium. For this reason, a backhitch needs to be performed. A backhitch is a series of operations that decrease the speed of the tape medium to stop the tape medium once, cause the tape medium to travel in a reverse direction and in a forward direction again to reach a position where next data should be written, and then write the data. The next data is not written until the backhitch is completed. A backhitch requires about 3 to 5 seconds and significantly degrades writing performance.
Recursive accumulating backhitchless flush (RABF) has been proposed as a technique for improving performance as it avoids data synchronization associated with a backhitch. However, RABF requires processing time for the movement between an accumulating backhitchless flush (ABF) and recursive wraps, writing the same data twice to the tape, and the like.